A flange is a type of fitting, and refers to a pipe joint such as an elbow or a tee which joins pipes. Such a flange may be used when a pipe is coupled to a different mechanical part.
Further, a flange such as a reinforcing flange is also used to increase a strength of a component in addition to when used for connection to the component such as in shaft coupling or pipe coupling.
Refrigerant pipes are connected to constituent elements such as a compressor, a condenser, an expansion valve, and an evaporator constituting a refrigeration cycle of an air conditioner such that a fluid can flow continuously. To improve a coupling force between the refrigerant pipe and the constituent element, a flange is fastened to ends of the refrigerant pipe. The flange for coupling the pipe is typically formed of plastic by injection molding. Since the plastic is relatively easily processed, the flange can be manufactured to exact dimensions including a thickness.
Meanwhile, for the purpose of the connection between the pipes as well as the reinforcement of the connection strength, a flange formed of a metal material such as stainless steel is required. As shown in FIG. 1a, a flange 10 generally includes a pipe portion 12 acting as a flange body, and an edge portion 14 having a disc shape. The pipe portion and the edge portion may be separately prepared and bonded by, for instance, welding. Otherwise, one pipe body may be partly cut and machined into a flange form. In the case of the cutting method, a flange can be machined to precise dimensions, but a waste of material is severe. When the flange is formed by welding, a fusion zone may be weak in strength.
To process the flange having precise dimensions, various methods can be used. For example, as shown in FIG. 1b, an edge 20b of a structure 20a having a pipe form may be first partly bent and machined into a form of a flange 22.
In the event of the machining based on the bending method, there is a problem that a thickness t1 of the pipe prior to the bending is different from a thickness t2 of the flange formed by bending.
Therefore, it is necessary to develop a new flanging method capable of maintaining process efficiency and a strength of a finally machined product while maintaining a uniform thickness.